NOTE: This a custom enchant module require TokenEnchant plugin.
This plugin contains a custom enchantment effect to let a player discover a key (such as a crate key) when a player mines a block. Server owners can customize a command to issue a key using the key plugin (such as a cratekey plugin).
Just install TE-KeyMinerEnchant.jar in TokenEnchant/enchants folder. Then you can either "restart the server" or "reload the plugin (not /te reload)". KeyMinerEnchantment will automatically be loaded into TokenEnchant framework.