The Gold Key is an item used in Adventure Mode to unlock Locked Doors. The key can be anywhere in a player’s inventory or hotbar for it to be used. Typically, mapmakers place Gold Keys in chests or dispensers. However, they can also be spawned in as either a mob drop or an item spawn by using the Customizable Mob Spawner.
Gold Key Hotbar Icon
A Locked Door being opened by a Gold Key