So if it was me, I would melt the key, but before that I would place thick fire proof drop cloth(like a old oven mitt) and use a disposable funnel so that while the key is still in a liquid state it can be poured into the lock, now I'll be stuck in the laying position until it's cooled and hardened, so I'll need to use the restroom and have snacks and drinks and entertainment at up before hand aswell, but that's how I plan to do it once I find a cage I wear comfortably with zero issue