Find the closest match to a cell , but with a condition.

Revert to SMALL from MIN such that you can adjust "k"

=SUM(IF(($B$3:$B$23>0)*ABS($A$3:$A$23-$F$1)=SMALL(ABS($A$3:$A$23*($B$3:$B$23>0)-$F$1),2),$A$3:$A$23))
confirmed with CTRL + SHIFT + ENTER

would return 5200 & 4300 for A:B, M:N respectively