SELECT 
  cscart_discussion.object_id AS product_id, 
  AVG(
    cscart_discussion_rating.rating_value
  ) AS average_rating, 
  cscart_discussion.type AS discussion_type, 
  cscart_discussion.thread_id AS discussion_thread_id 
FROM 
  cscart_discussion 
  LEFT JOIN cscart_discussion_posts ON cscart_discussion_posts.thread_id = cscart_discussion.thread_id 
  AND cscart_discussion_posts.status = "A" 
  LEFT JOIN cscart_discussion_rating ON cscart_discussion.thread_id = cscart_discussion_rating.thread_id 
  AND cscart_discussion_rating.post_id = cscart_discussion_posts.post_id 
  AND cscart_discussion_rating.rating_value != 0 
WHERE 
  cscart_discussion.object_id IN (
    10975, 5759, 1925, 11317, 10974, 11013, 
    11023, 11027, 11315, 11314, 11313, 
    11312, 11036, 11073, 11089, 11309, 
    11302, 10884, 11300, 11256, 11257, 
    11316, 10830, 11286, 11285, 11284, 
    11283, 3875, 11282, 10638, 10870, 11031, 
    11030, 10738, 11253, 11025, 11267, 
    11266, 11265, 11264, 11263, 11262, 
    11259, 11261, 10848, 10979, 11012, 
    11024, 11090, 11234, 11235, 11258, 
    11254, 11269, 10333, 11015, 11018, 
    11019, 11238, 11251, 11307, 11308, 
    11002, 10335
  ) 
  AND cscart_discussion.object_type = "P" 
  AND cscart_discussion.company_id = 1 
GROUP BY 
  cscart_discussion.object_id

Query time 0.00078

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "614.41"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_discussion",
            "access_type": "range",
            "possible_keys": [
              "object_id",
              "company_id"
            ],
            "key": "object_id",
            "used_key_parts": [
              "object_id",
              "object_type",
              "company_id"
            ],
            "key_length": "10",
            "rows_examined_per_scan": 64,
            "rows_produced_per_join": 64,
            "filtered": "100.00",
            "index_condition": "((`ea201_francemaqu`.`cscart_discussion`.`company_id` = 1) and (`ea201_francemaqu`.`cscart_discussion`.`object_id` in (10975,5759,1925,11317,10974,11013,11023,11027,11315,11314,11313,11312,11036,11073,11089,11309,11302,10884,11300,11256,11257,11316,10830,11286,11285,11284,11283,3875,11282,10638,10870,11031,11030,10738,11253,11025,11267,11266,11265,11264,11263,11262,11259,11261,10848,10979,11012,11024,11090,11234,11235,11258,11254,11269,10333,11015,11018,11019,11238,11251,11307,11308,11002,10335)) and (`ea201_francemaqu`.`cscart_discussion`.`object_type` = 'P'))",
            "cost_info": {
              "read_cost": "140.81",
              "eval_cost": "12.80",
              "prefix_cost": "153.61",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "thread_id",
              "object_id",
              "object_type",
              "type",
              "company_id"
            ]
          }
        },
        {
          "table": {
            "table_name": "cscart_discussion_posts",
            "access_type": "ref",
            "possible_keys": [
              "thread_id",
              "thread_id_2"
            ],
            "key": "thread_id",
            "used_key_parts": [
              "thread_id"
            ],
            "key_length": "3",
            "ref": [
              "ea201_francemaqu.cscart_discussion.thread_id"
            ],
            "rows_examined_per_scan": 3,
            "rows_produced_per_join": 192,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "192.00",
              "eval_cost": "38.40",
              "prefix_cost": "384.01",
              "data_read_per_join": "84K"
            },
            "used_columns": [
              "post_id",
              "thread_id",
              "status"
            ],
            "attached_condition": "<if>(is_not_null_compl(cscart_discussion_posts), (`ea201_francemaqu`.`cscart_discussion_posts`.`status` = 'A'), true)"
          }
        },
        {
          "table": {
            "table_name": "cscart_discussion_rating",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "thread_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "post_id"
            ],
            "key_length": "3",
            "ref": [
              "ea201_francemaqu.cscart_discussion_posts.post_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 192,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "192.00",
              "eval_cost": "38.40",
              "prefix_cost": "614.41",
              "data_read_per_join": "3K"
            },
            "used_columns": [
              "rating_value",
              "post_id",
              "thread_id"
            ],
            "attached_condition": "<if>(is_not_null_compl(cscart_discussion_rating), ((`ea201_francemaqu`.`cscart_discussion_rating`.`thread_id` = `ea201_francemaqu`.`cscart_discussion`.`thread_id`) and (`ea201_francemaqu`.`cscart_discussion_rating`.`rating_value` <> 0)), true)"
          }
        }
      ]
    }
  }
}