The Yubico brand sells several USB sticks that serve as a verification key for your online accounts. You only get access when the stick is in your PC. The latest model is the Security Key C NFC.
Suitable for devices with a USB-C input, but also, for example, smartphones with an NFC chip on board. Such login is considered very secure and more and more websites are supporting it.
On your key ring
You can easily attach the stick to your key ring through the hole in the casing. The Security Key C NFC costs 29 euros.