HI
You can use an index with the statement
%_HINTS oracle 'INDEX("<index name>")'
example:
SELECT DISTINCT bukrs vbeln kunag fkart waerk fkdat
FROM vbrk CLIENT SPECIFIED
INTO TABLE ti_factura
WHERE mandt = '400' and fkart IN p_fkart
AND fkdat between p_budat1 and p_budat2
%_HINTS oracle 'INDEX("Z01")'.
look to this document, may help you.
Performance Improvement using Indexes and ABAP Hints
Regards
Ibrahim