SELECT 
  * 
FROM 
  cscart_product_feature_variants 
WHERE 
  variant_id IN (
    5898, 1230, 1449, 1201, 1219, 5899, 1269, 
    1283, 5900, 1281, 5901, 1255, 1257, 
    5902, 5903, 5913, 5904, 5905, 5906, 
    5907, 5908, 1282, 1425, 1313, 1280, 
    1254, 5909, 1314, 1200, 5910, 5912, 
    1198, 1203, 1199, 5914, 1241, 5915, 
    5916, 5940, 1204, 5942
  )

Query time 0.00056

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": 41,
      "filtered": 100,
      "index_condition": "cscart_product_feature_variants.variant_id in (5898,1230,1449,1201,1219,5899,1269,1283,5900,1281,5901,1255,1257,5902,5903,5913,5904,5905,5906,5907,5908,1282,1425,1313,1280,1254,5909,1314,1200,5910,5912,1198,1203,1199,5914,1241,5915,5916,5940,1204,5942)"
    }
  }
}