For sake of simplicity, maybe you should consider using the Requests library.
An example with json response content would be something like:
import requests
r = requests.get('https://github.com/timeline.json')
r.json()
If you look for further information, in the Quickstart section, they have lots of working examples.
EDIT:
For your specific curl translation:
import requests
url="https://www.googleapis.com/qpxExpress/v1/trips/search?key=mykeyhere"
payload = open("request.json")
headers = {'content-type': 'application/json', 'Accept-Charset': 'UTF-8'}
r = requests.post(url, data=payload, headers=headers)