SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5631cc6a7478879bb923036c42624afa38ba37485018ac219068b215cf67b420' 
  AND token = 'OvTnl9zNHK1VD/SwDmMFSMIksDxRwosaZ1MPJw93suo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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