Stop listing limited key raffles as guaranteed drops.
At the very least have the item be (supplies limited), (chance at a key). It shouldn't just say:
"Watch for time_hours and get a KEY."
People are expecting keys when it says 'watch and get a key'. Other games do this as more of a psuedo open-test and it really is everyone gets a key.
So at the very least, just be transparent that the keys are very limited.
As it stands, keys that are just given without being linked to an account are another issue. Seemingly half of the keys via these sorts of drops, just end up on key sites after bots beat everyone to them.
Keys should just be applied to linked accounts to prevent reselling as much, any keys in the drop inventory screen should clearly say 'chance' in some form.