curl --request POST \
  --url https://app.cryptoprocessing.com/api/v2/exchange/fixed \
  --header 'Content-Type: application/json' \
  --header 'X-Processing-Key: <api-key>' \
  --header 'X-Processing-Signature: <x-processing-signature>' \
  --data '
{
  "sender_currency": "BTC",
  "receiver_currency": "EUR",
  "sender_amount": 0.003,
  "foreign_id": "test_foreign_id_0250",
  "price": "77314.26444333"
}
'

{
  "data": {
    "sender_currency": "BTC",
    "sender_amount": "0.00300000",
    "receiver_currency": "EUR",
    "receiver_amount": "231.94279333",
    "fee_currency": "BTC",
    "fee_amount": "0.00015000",
    "price": "77314.26444333",
    "id": 134704049,
    "foreign_id": "test_foreign_id_0250",
    "type": "exchange",
    "status": "processing"
  }
}