SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339305e431568705b8e88fa5a611ffc70e424285b5f14dfc10f69a6b5d045500' 
  AND token = 'GcIhbqXsGa8HapdKG/Lb2OFVTeVd4pxsmekeLDjhIWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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