I mean, worst case destructive removal or locksmith might be an option. Though it would be best if the keysafe itself were easily destructible in case of such emergencies, since the alternative might involve one or more of the following:
- bothering professionals with a sort of close-to-body work that they probably have not signed up for
- wasting first responders' time with an emergency of your own making
- staying in the belt for longer than what is considered healthy
Personally, I would recommend to put one key into the safe, and another into a sleeve with a uniquely numbered security seal that can be broken by hand in case of emergency. Your keyholder can check the integrity of the seal with photo verification if that makes you feel more secure, which would also be less invasive than any check they could do that your belt is actually locked on.
That would still keep you accountable to actually wearing the belt, so the only major loss over both keys being in the safe is that the thrill of being completely at someone else's mercy is lessened. But if your objective is controlling your habits, accountability and a barrier to easy touching should be a huge benefit either way.
Anything you can say about your keyholder and the relationship you have with them?