SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66dcbf58af9ad2bcfd16018a34d942a4d852a6fc6235cdcd52e586a98d92aa7c' 
  AND token = 'qNgeNZBemx9ehkhusXp2qEsGNvrOHUUogBHVRL2cK2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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