So, just as a reference here are the keys we're currently seeing as ones that will not be converted to gold or removed upon release of the patch -- if you have them they'd be put back into your normal inventory. This isn't necessarily a final list, and it's possible we could cut the list down even further before 4.2 releases.
黑铁酒吧钥匙 (BRD)
Secret Safe Key (BRD)
黑暗守护者钥匙 (BRD)
遗物宝箱钥匙 (BRD)
Jump-a-Tron 4000 Key (Nagrand)
科卡尔宝箱钥匙 (Barrens quest)
复仇军监牢钥匙 (Netherstorm – Blade’s Edge)
船长的钥匙 (Tanaris)
Any Blacksmith keys (e.g. Titanium Skeleton Key)