I was slack and didn't check over the weekend so apologies to the Borderlands 3 players as this code will expire in about 2 1/2 hours (11:00AM Eastern US Time). If you're quick, though, it'll give you 3 x Golden Keys to use on Sanctuary III:
The following keys, however, are for Borderlands: The Pre-Sequel and will be good until nearly midnight 10 August (11:59PM Eastern US Time, to be exact). Each will give you 5 x Golden Keys to redeem:
Note that you need a SHiFT account to redeem but you don't need to actually own the game, so you can be all OzBargain-y and redeem them anyway then enjoy them later when (or if) you get the games.