There is Bronze box, silver box, gold box near the Pirate Village General store NPC. Through NPC user can change bronze key to silver and silver to gold key. 10* bronze= 1 silver. 10 silver= 1 gold key.

Not Enough infomation for Him MATTE:

Matte Talk about change Key Bronze To Silver and Silver to Gold Key.

About Place to exchange Bronze Key. near NPC u change 10 key bronze to 1 Silver key.

Next to NPC u change Key Bronze to Silver . u will see next to u got 1 Gold Box ( i mean Box is Gold color not Gold box use +50%)

Jump or move to the top ( u can see when u below house) will see 2 more Box is Brzone Box for exchange bronze Key and Silver Box for exchange Silver Key.

When u talking with That Box ( Brzone Box,Silver Box or Gold Box) will drop rate up to Key u use.

Bronze is normal got C B or sometime A ( i not sure Brzone key because i no use it)

Silver key almost is A grade item (75 and 80 after update i no test also dont know)

About Gold key will same Silver key ( But got more Rare item - Stone...Lucky Ichiman + 100 luck and ...)

If u newbie no try test Gold key.

If my information not enough or something wrong after update .

Sorry about it.
IF still cant do ( Come MK Find -Baby-THORK) i will help u

Thanks You.
THORK

Ty Mate and Thork..i try

Dog Thork always says a lot ... by Google translate , hahaha ~

Pretty much quit the game after I spent 200m on a gold key and got an item worth next to nothing.

BabyThork has been a great resource for old returning players.. I wish I had seen this post 2 days ago.

Thanks a liat Thork... now i never sell my key