SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fe3d18d58adb8c1c9e7c5d67314a567db31e72307bc688ab851ee9fae40dec0' 
  AND token = 'U8h6lnzLJl7/4qIBCygJOxybjNj+jfQlMJKElQs+grU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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