findByで1件取得

findOneByXXX()で取得できます。

$this->hoge = Doctrine::getTable('Hoge')->findOneByHogeIdAndFugaId($hogeId, $fugaId);

findOneを使わない場合

$this->hoge = Doctrine::getTable('Hoge')->findByHogeIdAndFugaId($hogeId, $fugaId);
$this->hoge = $this->hoge[0];