SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac9712779708db43cb1470a495246e346d51fbed1852ae01d8f43f178c090d4a' 
  AND token = 'tzEYFjdNQr23Lq4SPly1ZPUFJdU4j+9G3IKCPq8VnYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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