SQL> select sid, serial#, last_call_et
  2  from   v$session
  3  where  sql_id = '0qht8ubcqk4wr'   -- the "problem" SQL_ID
  4  and    status = 'ACTIVE'
  5  order by 3;

       SID    SERIAL# LAST_CALL_ET
---------- ---------- ------------
       497        744           38
       136      13162           45
       373      28703           52

3 rows selected.

SQL> set serverout on
SQL> declare
  2    l_threshold int := 1;
  3    l_cnt       int := 0;
  4  begin
  5   for i in (
  6       select sid, serial#, last_call_et
  7       from   v$session
  8       where  sql_id = '0qht8ubcqk4wr'
  9       and    status = 'ACTIVE'
 10       order by 3
 11   )
 12   loop
 13     l_cnt := l_cnt + 1;
 14     if l_cnt <= l_threshold then
 15       dbms_output.put_line('Leaving SID='||i.sid||' untouched');
 16     else
 17       dbms_output.put_line('Killing SID='||i.sid);
 18       -- execute immediate 'alter system kill session ....';
 19     end if;
 20   end loop;
 21  end;
 22  /
Leaving SID=497 untouched
Killing SID=136
Killing SID=373

PL/SQL procedure successfully completed.