this is the query plan without the non clustered index which produced 9 table scans

|--Compute Scalar(DEFINE:([Expr1003]=CONVERT_IMPLICIT(int,[globalagg1005],0)))

|--Stream Aggregate(DEFINE:([globalagg1005]=SUM([partialagg1004])))

|--Parallelism(Gather Streams)

|--Stream Aggregate(DEFINE:([partialagg1004]=Count(*)))

|--Clustered Index Scan(OBJECT:([Wallet0000].[dbo].[EntityCollection].[PK_Entity]))

this is with the index i added

|--Compute Scalar(DEFINE:([Expr1003]=CONVERT_IMPLICIT(int,[Expr1004],0)))

|--Stream Aggregate(DEFINE:([Expr1004]=Count(*)))

|--Index Scan(OBJECT:([Wallet0000].[dbo].[EntityCollection].[idx_entity_identifier]))