curl -X GET https://api.mycentralino.com/v1/contacts/12345 \
  -H "X-API-KEY: sk_mycentralino_your_api_key"

<?php
$id = 12345;
$ch = curl_init("https://api.mycentralino.com/v1/contacts/{$id}");
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'X-API-KEY: sk_mycentralino_your_api_key'
    ]
]);

$response = curl_exec($ch);
curl_close($ch);

print_r(json_decode($response, true));

import requests

headers = {'X-API-KEY': 'sk_mycentralino_your_api_key'}
contact_id = 12345

response = requests.get(
    f'https://api.mycentralino.com/v1/contacts/{contact_id}',
    headers=headers
)
print(response.json())