This original query looks like using the primary key index  (T_D0, T_D1, T_D2) on Tmanykeys, getting rid of the order by node.

This is the original plan:
NESTLOOP INDEX INNER JOIN (ASC)
inline LIMIT with parameter
inline INDEX SCAN of "TMANYKEYS" using "SYS_IDX_T_TREE_3_10036"
range-scan on 1 of 3 cols from (T_D0 >= T.T_D2) while (T_D0 = T.T_D2)
 INDEX SCAN of "T" using "SYS_IDX_T_TREE_10020"
 range-scan on 1 of 2 cols from (T_D0 >= ?0) while (T_D0 = ?0)