Simulating timeout is not working

I am trying to simulate a timeout response when using wp_remote_get() for better debugging. This is the code I'm using:

set_time_limit( -0 );
ini_set('max_execution_time', 0);
$args = array(
    'headers' = array(
        'Content-Type'    = 'application/json',
        'timeout'         = 15,
    ),
);
$request_response = wp_remote_get( $this-token_url . 'sleep=10', $args );

This is the response (WP_Error):

cURL error 28: Operation timed out after 5000 milliseconds with 0 bytes received

1. It doesn't matter if I change the value of set_time_limit
2. It doesn't matter if I change the value of max_execution_time
3. It doesn't matter if I change the value of timeout (to 50 for example)

I still receive the cURL error after 5 seconds. Any idea why this is happening and how to solve it?

Thanks