SELECT 
  product_id, 
  feature_id, 
  variant_id 
FROM 
  cscart_product_features_values 
WHERE 
  product_id IN (
    12575, 12576, 12577, 12578, 12579, 12580, 
    12581, 12582, 12583, 12584, 12585, 
    12586, 12587, 12588, 12589, 12590, 
    12591, 12592, 12593, 12564, 12565, 
    12566, 12567, 12568, 12569, 12570, 
    12571, 12572, 12573, 12574, 12554, 
    12556, 12555, 12558, 12557, 12560, 
    12559, 12562, 12561, 12563
  ) 
  AND feature_id IN (624, 627, 628, 553, 625) 
  AND lang_code = 'en'

Query time 0.00509

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "7.83"
    },
    "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": "PRIMARY",
      "used_key_parts": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "key_length": "15",
      "rows_examined_per_scan": 20,
      "rows_produced_per_join": 20,
      "filtered": "100.00",
      "using_index_for_skip_scan": true,
      "cost_info": {
        "read_cost": "5.84",
        "eval_cost": "2.00",
        "prefix_cost": "7.84",
        "data_read_per_join": "15K"
      },
      "used_columns": [
        "feature_id",
        "product_id",
        "variant_id",
        "lang_code"
      ],
      "attached_condition": "((`test2_gaseus`.`cscart_product_features_values`.`product_id` in (12575,12576,12577,12578,12579,12580,12581,12582,12583,12584,12585,12586,12587,12588,12589,12590,12591,12592,12593,12564,12565,12566,12567,12568,12569,12570,12571,12572,12573,12574,12554,12556,12555,12558,12557,12560,12559,12562,12561,12563)) and (`test2_gaseus`.`cscart_product_features_values`.`feature_id` in (624,627,628,553,625)) and (`test2_gaseus`.`cscart_product_features_values`.`lang_code` = 'en'))"
    }
  }
}