mysql查询优化，谁能帮我优化查询啊？我这个太慢了，慢死了

SELECT mobileuserid,caozuoleixing,caozuozhi,xiguanzhi FROM 表A WHERE xiguanzhi>2
GROUP BY mobileuserid,caozuoleixing,caozuozhi,xiguanzhi
ORDER BY mobileuserid,caozuoleixing,xiguanzhi DESC LIMIT 3000