CoCart – Where Can I find or make a new Cart Key?

I am trying to make an app using Woocommerce and CoCart. CoCart is used for the cart items. It works fine when I am trying to add update and delete with JWT. But what to do with guest users?

So I read that you can use a cart_key in the params. However, do I need to make my own cart_key like: ‘12345’ or even better use a random character and number generator?

Or does CoCart gives you a cart_key when you put in a first item in the card and you call the endpoint without a JWT? (I tried this but if I do not put a cart_key without JWT I get an error message.

Do you have any experience?
Thanks!