SELECT 
  * 
FROM 
  jmj_product_feature_variants 
WHERE 
  variant_id IN (
    3246, 3247, 2334, 2339, 2353, 2354, 2355, 
    2363, 2373, 2366, 2369, 2371, 2372, 
    2376, 2639, 2129, 2232, 766
  )

Query time 0.01857

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "43.21"
    },
    "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": 18,
      "rows_produced_per_join": 18,
      "filtered": "100.00",
      "index_condition": "(`jmj_test`.`jmj_product_feature_variants`.`variant_id` in (3246,3247,2334,2339,2353,2354,2355,2363,2373,2366,2369,2371,2372,2376,2639,2129,2232,766))",
      "cost_info": {
        "read_cost": "39.61",
        "eval_cost": "3.60",
        "prefix_cost": "43.21",
        "data_read_per_join": "27K"
      },
      "used_columns": [
        "variant_id",
        "feature_id",
        "url",
        "color",
        "position",
        "abt__ut2_color_style",
        "abt__ut2_multicolor"
      ]
    }
  }
}