SELECT 
  * 
FROM 
  jmj_product_feature_variants 
WHERE 
  variant_id IN (
    3246, 3247, 2145, 2147, 2152, 2181, 2192, 
    2201, 2202, 766
  )

Query time 0.00066

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "24.01"
    },
    "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": 10,
      "rows_produced_per_join": 10,
      "filtered": "100.00",
      "index_condition": "(`jmj_test`.`jmj_product_feature_variants`.`variant_id` in (3246,3247,2145,2147,2152,2181,2192,2201,2202,766))",
      "cost_info": {
        "read_cost": "22.01",
        "eval_cost": "2.00",
        "prefix_cost": "24.01",
        "data_read_per_join": "15K"
      },
      "used_columns": [
        "variant_id",
        "feature_id",
        "url",
        "color",
        "position",
        "abt__ut2_color_style",
        "abt__ut2_multicolor"
      ]
    }
  }
}