Opening lockboxes is expensive and adding a way for anyone to unbox would massively benefit the economy and give people more reasons to unbox. With this change, slime lockboxes can no longer be opened with silver keys as that would make the slime key worthless. You get more silver keys depending on which orbs you use.

Silver Key Recipes **Slime Key recipes are the same but with Slime Fragments, which drop from the Golden Slime Casino Wheels and in vaults:

1 Silver Key
x10 Silver Fragments
x3 Advanced Orbs
1kcr

2 Silver Keys

x15 Silver Fragments
X3 Elite Orbs
2.5kcr

3 Silver Keys

x20 Silver Fragments
x3 Eternal Orbs
5kcr

Obtaining Silver Fragments
Silver fragments can be obtained in a variety of ways and come bound:

Completing an arcade run will award 1 fragment for every depth cleared. You must complete the run to receive them(hitting moorcroft, emberlight, or the core).
Completing prestige will award fragments, more from the danger mission.
Rare drop from Treasure Boxes.
You can redeem them with boss tokens.