When you purchase this key, you get to choose which of the 7 items you want. This is not luck based

In the server you can choose one of these:

Enchanted Netherite Helmet

Enchanted Netherite Chestplate

Enchanted Netherite Leggings

Enchanted Netherite Boots 

Enchanted Netherite Sword

Enchanted Crossbow

Enchanted Elytra