In this case, the query string represents a "saved search", and the design has worked fairly well over time.
One complication here is that some of the search values have multiple keys. If we were to use Codd's third normal form, we wouldn't have just one row per search, but a whole collection of table rows.
in reply to Re^3: CGI.pm: Want your query_string() sorted or unsorted?
in thread CGI.pm: Want your query_string() sorted or unsorted?
There are definitely other cases and future cases where I could consider putting each search value it's own database column.