php – select id where one column have a minimum value

column cat is varchar and column step is integer
need to select id where cat is lorem and step is minimum value
like this:

$sq = "select id from arts where cat = 'lorem' and step = min from step";

so if two rows have cat = lorem with step = 2 and 3 – the id of the first one should be selected
if another row – not having cat = lorem has step = 1 – it should be ignored
pls help