SELECT * FROM table
    WHERE owner = 'user'
      AND status IN ('NEW', 'CB','NA','NI','GC','FC')
    ORDER BY status = 'NEW' DESC,
             RAND() DESC
LIMIT 1;

将给你总共1行，给你一个随机的'新'的优惠。如果没有“新”行，则随机选择其他行。
（请澄清您的问题并提供示例输出。）

SELECT * FROM Table
WHERE owner = 'user'
AND (CASE WHEN (SELECT COUNT(*) FROM Table WHERE status = 'NEW') >= 1 THEN
                status = 'NEW'
     ELSE status IN ('CB','NA','NI','GC','FC')
     END)
ORDER BY RAND() DESC
LIMIT 1;

演示
http://sqlfiddle.com/#!9月9日B1C8/1

我想，你可以

SELECT * FROM table
WHERE owner = 'user'
AND (
   CASE WHEN status = 'NEW'
   THEN status = 'NEW'
   ELSE status IN ('CB','NA','NI','GC','FC')
   END
)
ORDER BY RAND() DESC
LIMIT 1;

到

SELECT * FROM table
WHERE owner = 'user' AND status IN ('NEW','CB','NA','NI','GC','FC')
GROUP By some_id
ORDER BY RAND() DESC
LIMIT 1;