SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6721aa8ff595ef2dff8ab11e7738007e28ea8cf5b2235acc7c3404e2b03352a9' 
  AND token = '8gvRyeuGwEa3g+BYuXo0GHwqn+KqjrMQbVXYTKnaKJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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