Best approach for subquery with trig functions?

$sql = "
    Select ID, Postcode, Lat, Lon, 
           acos(sin(:lat)*sin(radians(Lat)) + cos(:lat)*cos(radians(Lat))*cos(radians(Lon)-:lon)) * :R As D
    From (
      Select ID, Postcode, Lat, Lon
      From MyTable
      Where Lat Between :minLat And :maxLat
        And Lon Between :minLon And :maxLon
      ) As FirstCut 
    Where acos(sin(:lat)*sin(radians(Lat)) + cos(:lat)*cos(radians(Lat))*cos(radians(Lon)-:lon)) * :R < :rad
    Order by D";
  
  $params = array(
    'lat'    => deg2rad($lat), 
    'lon'    => deg2rad($lon), 
    'minLat' => $minLat,
    'minLon' => $minLon,
    'maxLat' => $maxLat,
    'maxLon' => $maxLon,
    'rad'    => $rad, 
    'R'      => $R,
  );
  $points = $db->prepare($sql);
  $points->execute($params);