import requests
s = requests.Session()
url = 'https://1xstavka.ru/testcupon/getresults/'
headers = {
    'Accept': 'application/json, text/javascript, */*; q=0.01',
    'Accept-Encoding': 'gzip, deflate, br',
    'Accept-Language': 'ru-RU,ru;q=0.9,en-US;q=0.8,en;q=0.7',
    'Connection': 'keep-alive',
    'Content-Length': '4',
    'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8',
    'Cookie': 'SESSION=3021a055790...', # куки передал целиком с браузера
    'Host': '1xstavka.ru',
    'Origin': 'https://1xstavka.ru',
    'Referer': 'https://1xstavka.ru/testcupon/',
    'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.108 Safari/537.36',
    'X-Requested-With': 'XMLHttpRequest'
}
r = s.post(url, {'num': '123456789'}, headers=headers)