Chastity and orgasm denial discussion

To keep my own key in check, I plan to place my device on and drop the key into a water bottle before freezing it. This way, when I’m ready to release myself, there will still be a couple of hours of waiting required before unlocking. My main concern is whether the ice might harm the keys. Should I put two keys in the bottle while leaving one out for emergencies? Also, what other self-holding methods have you all used?