SELECT 
  * 
FROM 
  cscart_product_feature_variants 
WHERE 
  variant_id IN (
    1230, 1449, 1201, 1219, 1269, 5900, 5901, 
    1255, 5903, 5913, 5904, 5907, 1425, 
    1280, 1254, 5909, 5912, 1203, 1199, 
    5914, 1241, 5915, 5916, 5940, 1204, 
    5942
  )

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_feature_variants",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["variant_id"],
      "rows": 26,
      "filtered": 100,
      "index_condition": "cscart_product_feature_variants.variant_id in (1230,1449,1201,1219,1269,5900,5901,1255,5903,5913,5904,5907,1425,1280,1254,5909,5912,1203,1199,5914,1241,5915,5916,5940,1204,5942)"
    }
  }
}