SELECT 
  * 
FROM 
  cscart_product_feature_variants 
WHERE 
  variant_id IN (
    4801, 4788, 4813, 4799, 4779, 4776, 4820, 
    4780, 4784, 4797, 2651, 1938, 2099, 
    1978, 4753, 1858, 1862, 1882, 2398, 
    2038, 1987, 1970, 2711, 3748, 5137, 
    2030, 1942, 1856, 1870, 1859, 0
  )

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_feature_variants",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 31,
          "filtered": 100,
          "index_condition": "cscart_product_feature_variants.variant_id in (4801,4788,4813,4799,4779,4776,4820,4780,4784,4797,2651,1938,2099,1978,4753,1858,1862,1882,2398,2038,1987,1970,2711,3748,5137,2030,1942,1856,1870,1859,0)"
        }
      }
    ]
  }
}