curl --request POST \
  --url {protocol}://{host}/wp-json/cocart/preview/my-account/subscriptions/{id}/payment-method \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "payment_method": "stripe",
  "token_id": 123
}
'

{
  "subscription_id": 123,
  "subscription_status": "<string>",
  "requires_payment": true,
  "payment_processed": true,
  "payment_method": "<string>",
  "payment_token": {
    "id": 123,
    "token": "<string>",
    "gateway_id": "<string>",
    "is_default": true,
    "expires": "12/2025"
  },
  "available_tokens": [
    {
      "id": 123,
      "token": "<string>",
      "gateway_id": "<string>",
      "is_default": true,
      "expires": "12/2025"
    }
  ],
  "can_use_token": true,
  "checkout_url": "<string>",
  "order_id": 123,
  "order_key": "<string>",
  "order_total": "<string>",
  "message": "<string>"
}