SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '507ad5b4a86c0bfea57fe869d523f12a9c067cd1b0def04e03812249a4a7deaa' 
  AND token = 'PHQPOUw932MMn++svoJDlcKhYhC9R957/Ykcqi+wZxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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