How to optimize Index Match for huge dataset

If columns are in the same order then
B3
=INDEX(G$3:G$7,MATCH($A3,$F$3:$F$7,1))
But if the number on table 1 might not exist on table 2, it still give result from big number that less than lookup value.

or try
=LOOKUP(1,1/($F$3:$F$7=$A3),G$3:G$7)