Problem on nearly every Realm is - you get those Keys (Ancient Guo-Lai Cache Key) from doing you daily quests or just killing mobs in Vale of Eternal Blossoms and the Cache spawn is really really rare.
If you look on your map in Guo-Lai Halls you can see there are a few locked doors (yellow) you can easily bypass with your Puntable Marmot (drop really close to the door an press interact with target two or three times) or just die in front of a locked door and rezz behind them! In there you can farm some mobs to get keys too and you'll find up to four Caches to open for yourself (maybe more, they spawn again really fast if people loot them "outside") (red areas)
Have fun getting your Golden Lotus rep before others.
/e i forgot to mention, we got an achievement there too (www.wowhead.com/achievement=7323) thanks viralsky !