Hi Jorge!
Checking the documentation of the API, I found this: https://developers.hubspot.com/docs/api/crm/search. I think you should do a POST REST call to this Location:
https://api.hubapi.com/crm/v3/objects/contacts/search?hapikey=YOUR_HUBSPOT_API_KEY
And inside the body of the request you can put some filters:
{
    "filterGroups":[
      {
        "filters":[
          {
            "propertyName": "firstname",
            "operator": "EQ",
            "value": "Alice"
          }
        ]
      }
However if you want to avoid the filter via API. Mendix can do it easily. Just map all the contacts to a Mendix entity of your Domain model and retrieve what you want using a XPath constraint.
If you have more doubts, please let me know.
Kind regards,
Emilio
Thank you very much for your answer emilio.
I find that request method interesting through a POST with the filter inside the body.
I have tested it and it works correctly!