I can't see how scalar @art could ever return a negative number, so your >0 check is probably overkill.

print "found" if scalar @ary;
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But, given that grep in scalar contents returns the number of matches, I'd probably skip the temporary value and use:

print "found" if grep { /one/ } values %hash;
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Oh, and using a regex to match a fixed string is inefficient.

print "found" if grep { $_ eq 'one' } values %hash;
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And we're pretty much back to my first solution :)