Performance issue

Hi,

I have a Custom table for USERDETAILS, on which I am fetching data using

SELECT ecno bname department l1name l2name bukrs

FROM yusrdetail

INTO TABLE vt_yusrdetail1

WHERE essid IS not NULL

AND department IN s_dept

AND bukrs IN s_bukrs.

Here how can I improve performance of this Query with out creating index on DEPT and BUKRS.

INDEX is already existing on ESSID.

Here BNAME is the only Primary Key available on this table.

It is very urgent Plz....

Thanx

K P