To find the index associated with table

column table_owner format a15
column table_name format a20
column index_name format a20
column column_name format a20

Select table_owner, table_name, index_name, column_name
FROM dba_ind_columns
Order by table_owner, table_name, column_name
Where table_owner=’OWNER_NAME’
AND table_name=’TABLE_NAME’;