There are several Keys that can be obtained from Traders.
Once a player has obtained a key, they can head to XYZ: 5 68 78 in Spawn, or use /crates to teleport. They can then head over to the related crate and right-click with the Key to open and receive a reward.
Obtaining
Vote Key
Vote Keys can be obtained by trading 5x Vote Shards at the Vote Trader.
Pyrite Key
Pyrite Keys can be obtained rarely from the Mining Crate, Farming Crate, Combat Crate, Fishing Crate, and Forest Crate.
Mining Key
Mining Keys can be obtained by trading 64x Diamond Blocks from Matt Allurgy or from the Vote Crate.
Farming Key
Farming Keys can be obtained by trading 128x Hay Bales from the Farmer or from the Vote Crate.
Combat Key
Combat Keys can be obtained by trading 5x Nether Stars from Captain Saltspring or from the Vote Crate.
Fishing Key
Fishing Keys can be obtained by trading 64x Pufferfish from the Fish Merchant or from the Vote Crate.
Forest Key
Forest Keys can be obtained by trading 64x Resin Blocks from Clara Chairman or from the Vote Crate.