SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '335aa95b6038d83db719b7048baa32283f533b345689045ee764123adbe9d2fa' 
  AND token = 'r1aejfUU9AkgvjWPf1XGAhEl5tTz1mk8C9NuZnmV++Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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