SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50b24155264e60f8695a15cac60adb042e5ce925e973357cb61905b1ea920d2' 
  AND token = 'pyUJwDCnzmLSL8UdTFosjByD1Wf0fEo1wHYIIrvyD8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}