I think I have found the solution for long term key storage if you live in a place where tornadoes or hurricanes are a problem.
Putting your key on metal is a must and protects against Fire and Water damage but doesn’t help if it gets blown away in a tornado. Good luck finding it in a 3 mile debris field.
Take a piece of PVC pipe, put the key on metal inside, seal with two end caps and PVC cement. Bury the whole thing. Extra points if you make a pirate treasure map. 🏴☠️