Extending Cookie Expiry in nginx

I am using nginx as a proxy between a front end and an API.
When the API returns a token, nginx sets it as a cookie.
The cookie will either have an expiry of 30 minutes, or 14 days if the user ticked ‘remember me’

If they didn’t tick remember me, I want the user to be logged out after 30 mins of inactivity, so on every request, if the cookie exists, I add it again with a new expiry of 30 minutes. However, if the user chose ‘remember me’ the original cookie has 14 day expiry and I don’t want to shorten it!

Is there anyway to do something conditionally on based on the expiry of a cookie? Or I could store the expiry in a different cookie but I still don’t know how to do anything conditionally on a date value. This is my config so far:

# Determine max-age for cookie on initial login
map $arg_remember $cookie_max_age {
    "true" "Max-age=1209600";
    "false" "Max-age=1800";
}

# Make a cookie if an x_my_token header was returned by API 
map $sent_http_x_my_token $header_to_cookie {
    "" $extend_cookie;
    default "my_token=$sent_http_x_my_token; path=/; HttpOnly; Secure; SameSite=Strict; $cookie_max_age";
}

# This map extends the cookie by 30mins if it exists
map $cookie_my_token $extend_cookie {
    ""  "";
    default "my_token=$cookie_my_token; path=/; HttpOnly; Secure; SameSite=Strict; Max-age=1800";
}

server {
    ...

    location /api/ {
        ...
        proxy_set_header Authorization "Bearer ${cookie_my_token}";
        add_header Set-Cookie $header_to_cookie;
    }
    
}

Thanks for any advice