Borderlands 2‘s Golden Key will be used to unlock a special Golden Chest in the city of Sanctuary, but there’s a few things to keep in mind before you go and open it.
You will only get one Golden Key so pick your moment carefully, inside the chest is incredibly rare loot which scales to your characters level, so opening it too early means that you’ve blown your chance of some amazing gear. The loot inside the chest can be traded or sold, but the keys can’t meaning you only get one shot.
In order to secure a Golden Key, you’ll need to get the Premier Club bonus which is available by pre-ordering Borderlands 2 at select retailers.
Update: Initial information about how to obtain Golden Keys was incorrect.