I have a table with an unindexed date column in a table of billions of rows

I collect the lowest and highest primary keys between those dates into variables

I set two variables

declare @min-2 int

declare @max-2 int

select @min-2 = min(primarykey) where datecol => 'begindate'

select @max-2= max(primarykey) where datecol <= 'enddate'

select primarykey, datecol, x,y,z from table where primarykey between @min-2 and @max-2

works for me