SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '50481df9342df195af0376d630eeba5ac1f53d0145bcd266474e9b8cf9d8a85d' 
  AND token = 'lFymfYQESbCrw7YMwVcVXCVqH78Ilq+xhR7ZvNahuFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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