SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    11236, 11235, 11234, 11233, 11232, 11231, 
    11230, 11229, 11228, 11227, 11226, 
    11225, 11224, 11223, 11222, 11221, 
    11220, 11219, 11218, 11217, 11216, 
    11215
  ) 
  AND feature_id IN (553, 624, 623) 
  AND lang_code = 'en'

Query time 0.00306

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "16.04"
    },
    "table": {
      "table_name": "cscart_product_features_values",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "fl",
        "lang_code",
        "product_id",
        "fpl",
        "idx_product_feature_variant_id"
      ],
      "key": "idx_product_feature_variant_id",
      "used_key_parts": [
        "product_id",
        "feature_id",
        "lang_code"
      ],
      "key_length": "12",
      "rows_examined_per_scan": 69,
      "rows_produced_per_join": 69,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "9.14",
        "eval_cost": "6.90",
        "prefix_cost": "16.04",
        "data_read_per_join": "53K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`gaseus`.`cscart_product_features_values`.`product_id` in (11236,11235,11234,11233,11232,11231,11230,11229,11228,11227,11226,11225,11224,11223,11222,11221,11220,11219,11218,11217,11216,11215)) and (`gaseus`.`cscart_product_features_values`.`feature_id` in (553,624,623)) and (`gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}