SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f279483799cc8d45665289163c56ea26a157db4d22fee8966bd9fe6f6c900d' 
  AND token = 'C09TWHMBQMYRZQnvMhw+4JZM/T33bS//+C8XndXivZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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