for rather small values that are OK, this seems to be the fastest solution:

my @ok=(0,0,0,1,0,1,0,1);
#       0 1 2 3 4 5 6 7

my $x = 4;
my $y = 5;

if($ok[$x]){print "$x is ok\n";}
if($ok[$y]){print "$y is ok\n";}
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if your OK-values get larger, I would use a hash instead of an array!