SQL>select  * from cprd
  2  where cprd.nprodver = :nprodver
  3  AND   cprd.strprodcd = :strprodcd
  4  ;

Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=1335 Card=15342 Byte
          s=1334754)

   1    0   TABLE ACCESS (BY INDEX ROWID) OF 'CPRD' (Cost=
          1335 Card=15342 Bytes=1334754)

   2    1     INDEX (RANGE SCAN) OF 'CPRD_IDX' (NON-UNIQ
          UE) (Cost=60 Card=15342)



select num_rows,blocks from user_tables where table_name='CPRD'
NUM_ROWS	BLOCKS
55923223	971229

select leaf_blocks,distinct_keys,avg_leaf_blocks_per_key,avg_data_blocks_per_key,clustering_factor,num_rows from user_indexes where index_name='CPRD__IDX'
LEAF_BLOCKS	DISTINCT_KEYS	AVG_LEAF_BLOCKS_PER_KEY	AVG_DATA_BLOCKS_PER_KEY	CLUSTERING_FACTOR	NUM_ROWS
203848	140	1456	41722	5841106	52737933


select column_name,nullable,num_distinct,num_buckets from user_TAB_COLUMNS where table_name='CPRD' AND COLUMN_NAME IN('STRPRODCD','NPRODVER')
COLUMN_NAME	NULLABLE	NUM_DISTINCT	NUM_BUCKETS
STRPRODCD	N	81	79
NPRODVER	Y	45	44

Computing histograms with size 254 for both index key columns produced following plan

SQL>select  * from  cprd
  2  where cprd.nprodver = :nprodver
  3  AND   cprd.strprodcd = :strprodcd;

Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=252 Card=7744 Bytes=
          681472)

   1    0   TABLE ACCESS (BY INDEX ROWID) OF 'CPRD' (Cost=
          252 Card=7744 Bytes=681472)

   2    1     INDEX (RANGE SCAN) OF 'CPRD_IDX' (NON-UNIQ
          UE) (Cost=32 Card=7744)