SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '310e2d8a3dad9d272f729b3a3aa18185056ccc34b6a48f855b5935f21f53c996' 
  AND token = 'Bs3fuJVGRnWyv362xQFA+u/+LXv52wzKz1eRiKPgy68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}