How to use the csrf class in codeigniter with onchange event?

I have the following situation:

Form

<?php
    $atributos = array('id'=>'cadloja','class'=>'form-inline','role'=>'form','data-toggle'=>'validator');
    echo form_open('',$atributos);
?>
    <select class="form-control" id="grupo">
        <option value="<?= 'retorno_ajax' ?>"><?= 'retorno_ajax' ?></option>
    </select>

<?php
    echo form_close();
?>

Javascript

$('#grupo').change(function () {
    $('#div_retorno').load('lista_grupos');
}

Notice that I'm not using ajax requests or submitting the form in the onchange event. With csrf active, onchange no longer works.

I even found some answers in SOen , but in all, I would be forced to make another ajax request in the onchange event. I also read in the documentation of CI that it is possible to delete a page from csrf :

 $config['csrf_exclude_uris'] = array('controllerx/metodox');

This option is the one that gives less work, but would you still be safe?

So, that's it ... is there any way you can do other than the two I said? Thank you.