How long does the one-time use SSH public key expire?

I'm interested in the recent feature https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Connect-using-EC2-Instance-Connect.html .

The doc says there is a one-time use SSH public key that only remains 60 seconds.

But I tried it by self, looks like the one-time SSH public key always is valid after pushing it via cli. I can still use the corresponding private key to login the instance after pushing public key more than 10 minutes.

Is it expected behavior? How should I understand the one-time use SSH public key mentioned in doc?