In this particular case, since you want the two counts...

SELECT q1, q2 FROM

(SELECT Count(a.PK) as q1 FROM Table1 as a) t1,

(SELECT Count(b.PK) as q2 FROM Table2 as b) t2

Only in this case though.

In general the question can't be answered. How can you meaningfully join two completely unrelated tables and have the columns related to each other? If they are completely unrelated, then they probably shouldn't even be in the same query