SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7d5538ab710e681888052c92fffc2f65da08ffb5a54d3ecdfe2916b11c977560' 
  AND token = 'MuFwaAcTYG7F2IOF+aBrqWdKp05swIjn/IKwJv6YtDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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