Query waiting on index

 One of our developers complains that a session just hung there. I was able to catch the sql statement with the OS pid and got the execution plan. It is using index scan, but somehow, the query is waiting on the index. My database version is 10.2.0.3 on solaris 10. The table has 668042 rows in it. Below is the statement and the plan:

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
SQL_ID  5456tabbxjbwy, child number 0
-------------------------------------
SELECT /*+FIRST_ROWS INDEX_ASC(a ttiitm952100$idx3)*/
a.t$copt$1,a.t$copt$2,a.t$copt$3,a.t$copt$4,a.t$copt$5,a.t$copt$6,a.t$copt$7,a.t