You will get 5x  Nostalgia Key

You can get following rewards from the crate:

1% - 1x Gambler Sword
5% -24x Gamble Powder
14% - 1x Maze Key
15% - 6x Compressed Coins
20% - 1x Moon Key
20% - 1x Maze Fragment
25% - 4x Antique Key

!! WARNING !! YOU WILL GET THE KEY(s) STRAIGHT INTO YOUR INVENTORY
-- REMEMBER TO CLEAN UP SPACE IN YOUR INVENTORY,
AND TO BE IN A SAFE POSITION WHERE YOU CAN'T GET KILLED --