wordpress-meta-query-multiple-keys.php

<?php
$args = array(
  'meta_query' => array(
    'relation' => 'AND',
    array(
      'key'     => 'city_name',
      'value'   => array('New York City', 'London', 'San Francisco'),
      'compare' => 'IN',
    ),
    array(
      'key'     => 'featured_post',
      'value'   => '1',
      'compare' => '=',
    ),
  ),
);

$q = new WP_Query( $args );