SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    11121, 11130, 11131, 11132, 11126, 11127, 
    11128, 11129, 11122, 11123, 11124, 
    11125, 11120, 11119, 11118, 11117, 
    11116, 11115, 11114, 11113, 11112, 
    11111
  ) 
  AND feature_id IN (553, 624, 623) 
  AND lang_code = 'en'

Query time 0.00318

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "18.05"
    },
    "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": 78,
      "rows_produced_per_join": 78,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "10.25",
        "eval_cost": "7.80",
        "prefix_cost": "18.05",
        "data_read_per_join": "60K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`gaseus`.`cscart_product_features_values`.`product_id` in (11121,11130,11131,11132,11126,11127,11128,11129,11122,11123,11124,11125,11120,11119,11118,11117,11116,11115,11114,11113,11112,11111)) and (`gaseus`.`cscart_product_features_values`.`feature_id` in (553,624,623)) and (`gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}