SELECT 
  * 
FROM 
  jmj_product_feature_variants 
WHERE 
  variant_id IN (
    3246, 3247, 1304, 1308, 1315, 1317, 1319, 
    1320, 1321, 1322, 1328, 1331, 2141, 
    2205, 766
  )

Query time 0.00138

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "36.01"
    },
    "table": {
      "table_name": "jmj_product_feature_variants",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "variant_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 15,
      "rows_produced_per_join": 15,
      "filtered": "100.00",
      "index_condition": "(`jmj_test`.`jmj_product_feature_variants`.`variant_id` in (3246,3247,1304,1308,1315,1317,1319,1320,1321,1322,1328,1331,2141,2205,766))",
      "cost_info": {
        "read_cost": "33.01",
        "eval_cost": "3.00",
        "prefix_cost": "36.01",
        "data_read_per_join": "23K"
      },
      "used_columns": [
        "variant_id",
        "feature_id",
        "url",
        "color",
        "position",
        "abt__ut2_color_style",
        "abt__ut2_multicolor"
      ]
    }
  }
}