SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ff3af009d39032cb717ba29f507aae41e127a62415ac5bc22c5644c129d75324' 
  AND token = 'tveSW/QldpeSBljoPycQxJBfYY3Gg6wBRVZUVo2b06E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}