Here is a simple array_replace_keys function:

/**
     * This function replaces the keys of an associate array by those supplied in the keys array
     *
     * @param $array target associative array in which the keys are intended to be replaced
     * @param $keys associate array where search key => replace by key, for replacing respective keys
     * @return  array with replaced keys
     */
    private function array_replace_keys($array, $keys)
    {
        foreach ($keys as $search => $replace) {
            if ( isset($array[$search])) {
                $array[$replace] = $array[$search];
                unset($array[$search]);
            }
        }

        return $array;
    }

// Test Drive

print_r(array_replace_keys(['one'=>'apple', 'two'=>'orange'], ['one'=>'ett', 'two'=>'tvo']);
// Output
array(
'ett'=>'apple',
'tvo'=>'orange'
)