Advanced Search Word Limitations

[RiskyFlame]

When I use the 'Advanced Search' and I want to search a specific word that only is made up out of three characters, it says

Sorry - no matches. Please try some different terms.
The following words are either very common, too long, or too short and were not included in your search : key

This message I get at least once out of ten times, mostly when containing three charaters, sometimes when the word is too common. Normally I also select 'Search titles only'.

So I start thinking: not that many threads have a title with the word 'key' in it.

So my question right now is:
Why is there a minimum limit of characters? Also can this limit be removed?