Originally Posted by ISTFlyer

Unless you are traveling at a "P" fare class ticket, yes, you could upgrade to Al Safwa at the entrance of Al Safwa for QAR 650 ( about $180 ).
Although a reminder that paid access would only allow you 6 hours in Al Safwa and after that time exceeds, you either need to pay again the QAR 650 or move to Al Mourjan. I know that your layover is 3h, but wrote this just in case other members get this post as a reference.