Query is -

select customer_id from CUSTOMER w
where upper(class_a_customer_id) = upper('CUSTDTH') AND customer_category_cd =1 AND is_user_manager = 2

PLAN_TABLE_OUTPUT -
 
--------------------------------------------------------------------------------------------
| Id  | Operation                   |  Name                        | Rows  | Bytes | Cost  |
--------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                              |  2117 | 50808 |   484 |
|*  1 |  TABLE ACCESS BY INDEX ROWID| CUSTOMER                     |  2117 | 50808 |   484 |
|*  2 |   INDEX RANGE SCAN          | NDX_T_CUSTOMER_CLASSACUSTID  | 12697 |       |    41 |
--------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   1 - filter("CUSTOMER"."CUSTOMER_CATEGORY_CD"=1 AND "CUSTOMER"."IS_USER_MANAGER"=2)
   2 - access(UPPER("CUSTOMER"."CLASS_A_CUSTOMER_ID")='CUSTDTH')
 
Note: cpu costing is off

How can I optimize the query. Please guide me.