SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '355205df26050e265cab19b168ec15b91d36e639acc4ba355e2ab4cd0bc03cb3' 
  AND token = '6a1g7VpBdcTdbHcsTdleUMYKqKZcycZmaer/GfsM/nM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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