SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6817a4fa0ecddb792997b98c589ac732fd98013a065119f0b89e441af34673bb' 
  AND token = 'RA58trbgCGUH9UyIgayzN44PhEkibUPeRlBkab4bgPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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