SELECT 
  * 
FROM 
  ushop_product_feature_variants 
WHERE 
  variant_id IN (3907, 0)

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.41"
    },
    "table": {
      "table_name": "ushop_product_feature_variants",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "variant_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 2,
      "rows_produced_per_join": 2,
      "filtered": "100.00",
      "index_condition": "(`marketplace`.`ushop_product_feature_variants`.`variant_id` in (3907,0))",
      "cost_info": {
        "read_cost": "1.21",
        "eval_cost": "0.20",
        "prefix_cost": "1.41",
        "data_read_per_join": "3K"
      },
      "used_columns": [
        "variant_id",
        "feature_id",
        "url",
        "color",
        "position",
        "abt__ut2_color_style",
        "abt__ut2_multicolor",
        "second_color"
      ]
    }
  }
}