Manipulate keys values in foreach

foreach.php

<?php 
    /**
     * @param array $array
     *
     * @return array
     */
    protected function translate($array)
    {
        $filtersChoicesTrans = [];
        foreach ($array as $key => $value) {
            $keyToLower = strtolower($key);

            $filtersChoicesTrans["monolog.event.{$keyToLower}"] = $value;
        }

        return $filtersChoicesTrans;
    }