select query takes 13 seconds to run with index

Hi, is there anyway this can be made faster?  id is the primary key,
and there is an index on uid..

thanks


EXPLAIN ANALYZE select * from pokes where uid = 578439028 order by id
DESC limit 6;
                                                                     QUERY PLAN

----------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..9329.02 rows=6 width=135) (actual
time=13612.247..13612.247 rows=0 loops=1)
   ->  Index Scan Backward using pokes_pkey on pokes
(cost=0.00..5182270.69 rows=3333 width=135) (actual
time=13612.245..13612.245 rows=0 loops=1)
         Filter: (uid = 578439028)
 Total runtime: 13612.369 ms
(4 rows)