Yes, the lexical variables are part of the absolute timings.

However, it's the relative timings that are of interest in this case as the point of the exercise was to assess the difference between exists $h{$k} or $h{$k}. If all other components are held constant then the timing differences should be due to the use of either of the two idioms (noting that the benchmarks need to be updated given dave_the_m's comments in 341121).