Nevermind, I figured it out. I placed the <= and >= in the wrong places. And need to format the current date ($dt) It should have been:

my $mydatarow = $schema->resultset( 'DataTable' )->search({ START_DATE
+ => { '<=' => $dt }, END_DATE     => { '>=' => $dt->ymd() }})->single
+;
[download]

Thanks anyway!