what do you get for this targeting the columns in that Index
;with cte
as
(
select PARPRT_02,'349-00006001-03' as COMPRT_02,'2018-10-10' as EFFDTE_02,'' as ALTCDE_02
FROM [Product_Structure]
WHERE PARPRT_02 LIKE '41%
)
select PARPRT_02,COMPRT_02, EFFDTE_02, ALTCDE_02, count(1)
from cte
group by PARPRT_02,COMPRT_02, EFFDTE_02, ALTCDE_02
havinng count(1) > 1