ext_pillar:
  - mysql:
      mysql_query: 'SELECT machine_variables.name as pillar, machine_variables.val as value FROM machine_variables LEFT JOIN machines on machine_variables.machine_id = machines.id WHERE machines.machinename = ''%s'''

Note...I found using %S standard before modifying the python it wouldn't concat the string...you should now see the line:

    thisquery = mysql_query % (minion_id,)


Sorry I'm not a python guru, but at least it works :)