INDEX generation does it help with my selct querry

Can anyone suggest the best way to write the select statement below is my select statement and my INDEX XXX...

I'm not sure how much it will effect the performance ...can someone throw some light on my issue..

My Index is XXX in BSIS table with bukrs hkont gjahr monat prctr kostl in sequence

SELECT bukrs hkont gjahr belnr buzei

monat dmbtr kostl prctr xref3 shkzg budat bldat

FROM bsis

INTO CORRESPONDING FIELDS OF TABLE itab

WHERE bukrs IN bukrs

AND hkont IN hkont

AND gjahr EQ gjahr

AND monat EQ monat

AND prctr IN prctr

AND kostl IN s_kostl.