Query Tuning-very Urgent

Question

Beloq query is taking time to execute and cost is 934.
The db in which it is run has lesser volume of data compared to that of prod.
There is a full table scan on psd
inspite of a pk present on table psd columns (psd_id,psd_serial_no)
also a pk present on table ltc_iss_rec columns(ltc_iss_rec_id,psd_serial_num)
Pl help to optimize the query.
select a.psd_id,a.psd_serial_no,a.sys_id,a.cosmos_ref_no,a.src_sys_asgn_ref_no,
a.bank_id,b.lc_expr_dt
from psd a,ltc_iss_rec b
where ((b.ltc_iss_rec_id >= 'T200203140731163') and (b.ltc_iss_rec_id <= 'T200606224485207'))
and a.psd_id = b.ltc_iss_rec_id
and a.psd_serial_no = b.psd_serial_num
and a.psd_typ_cod = 'ISS'
and b.lc_expr_dt <= '13-Mar-07'
and a.psd_serial_no =
select nvl(max(link_psd_ser_no),'000') from psd_link c,psd_lcs d
where c.psd_id = d.psd_id
and c.psd_serial_no = d.psd_serial_num
and c.link_psd_id = a.psd_id
and c.link_psd_id >= 'T200203140731163' and c.link_psd_id <= 'T200606224485207'
and d.update_serial_num = (
select max(update_serial_num) from psd_lcs e
where e.psd_id = d.psd_id
order by a.psd_id
Explain plan for the query :
Operation     Object Name     Rows     Bytes     Cost     Object Node     In/Out     PStart     PStop
SELECT STATEMENT Optimizer Mode=CHOOSE          1           934                     
SORT ORDER BY          1      96      900                     
FILTER                                        
NESTED LOOPS          1      96      898                     
PARTITION RANGE ALL                                   1     2
TABLE ACCESS FULL     IWH_OWNER.PSD     61      4 K     837                1     2
TABLE ACCESS BY GLOBAL INDEX ROWID     IWH_OWNER.LTC_ISS_REC     1      26      1                1     1
INDEX UNIQUE SCAN     IWH_OWNER.XPKLTC_ISS_REC     1                               
SORT AGGREGATE          1      112                          
HASH JOIN          1      112      34                     
TABLE ACCESS BY GLOBAL INDEX ROWID     IWH_OWNER.PSD_LCS     1      40      2                ROWID     ROW L
NESTED LOOPS          1      82      5                     
TABLE ACCESS BY GLOBAL INDEX ROWID     IWH_OWNER.PSD_LINK     1      42      3                ROWID     ROW L
INDEX RANGE SCAN     IWH_OWNER.XIE1PSD_LINK     1           2                     
INDEX RANGE SCAN     IWH_OWNER.XIE1PSD_LCS     2           1                     
VIEW     SYS.VW_SQ_1     134 K     3 M     26                     
SORT GROUP BY          134 K     4 M     26                     
INDEX FULL SCAN     IWH_OWNER.XIE1PSD_LCS     217 K     7 M     26

Answer 1

Read this link.
When your query takes too long ...
If you really need help from any of the forum members then you should avoid using the word "urgent" and give more useful information (check the above link what I meant by useful information) rather than simply saying it's very urgent please help me. It's of no use to anybody.
Regards
Raj