SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e74efd0795b59a4470319861392d1061331a524623e53d404296c2edcef5ec90' 
  AND token = 'Lh1Ka41A1TDbjDqt09QkY+dog85VBuPUB7aWOTc8Y3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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