Question regarding blocking lock

I have the following query:

select bs.sid, bs.serial# as serial
from v$lock hk, v$session bs, v$lock wk, v$session ws
where hk.lmode!=0
and hk.lmode!=1
and wk.request!=0
and wk.type(+)=hk.type
and wk.id1(+)=hk.id1
and wk.id2(+)=hk.id2
and hk.sid=bs.sid(+)
and wk.sid=ws.sid(+)
and (bs.username is not null);

It returns a potential blocking lock with sid 1759 and serial 838.

However, when I query select * from v$lock where sid=1759. It returns no rows selected.

Why is that? Is the first query alone enough to tell whether there is a blocking lock? Thanks.