SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    11106, 11107, 11105, 11104, 11103, 11102, 
    11101, 11100, 11099, 11098, 11097, 
    11096, 11095, 11094, 11093, 11092, 
    11091, 11090, 11089, 11110, 11109, 
    11108
  ) 
  AND feature_id IN (553, 624, 623) 
  AND lang_code = 'en'

Query time 0.00404

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 (11106,11107,11105,11104,11103,11102,11101,11100,11099,11098,11097,11096,11095,11094,11093,11092,11091,11090,11089,11110,11109,11108)) and (`gaseus`.`cscart_product_features_values`.`feature_id` in (553,624,623)) and (`gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}