SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c442161a45055bca64ee65f262b9659b6c4746cc8c549fd023df22979ba491f' 
  AND token = '4uZhBZ45zPl8DqNwkVzioeEuXwfJgEcwKj9fBcyJFjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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