They can be obtained via in-app purchases, daily rewards or by leveling up.
- 1 Chest Key: $0.99 US
- 3 Chest Keys: $US
- 13 Chest Keys: $9.99 US
- 28 Chest Keys: $????? US
- The 3D Key under the "Keys" tab does not actually rotate around 360 degrees like the 3D chest underneath it and instead oscillates.