WordPress query for a custom post type of "Events" that sorts by custom fields made in Advanced Custom Fields called "staart_date" and "start_time". I use two different fields because I wanted more control to do things like this.

query.php

<?php
return array(
    'post_type' => 'events',
    'posts_per_page' => '5',
    'meta_key' => 'start_date',
    'meta_query' => array(
        'relation' => 'AND',
        'date_clause' => array(
            'key' => 'start_date',
            'compare'	=> '=',
        ),
        'time_clause' => array(
            'key' => 'start_time',
            'compare'	=> '=',
        ),
        array(
            'key' => 'start_date', // Check the start date field
            'value' => date("Y-m-d"), // Set today's date (note the similar format)
            'compare' => '>=', // Return the ones greater than today's date
            'type' => 'DATE' // Let WordPress know we're working with date
        ),
    ),
    'orderby' => array(
        'date_clause' => 'ASC',
        'time_clause' => 'ASC',
    )
);

You can do it with a single Date Time field:

'post_type' => 'event',
'meta_key' => 'event_start_datetime',
'orderby' => 'meta_value', // order by start date/time
'order' => 'ASC',

// Only retrieve future events
'meta_query' => array(
    array(
        'key' => 'event_end_datetime',
        'value' => date('Y-m-d H:i:s'),
        'compare' => '>=',
        'type' => 'DATETIME'
    )
)

Thanks @shanomurphy!