SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd21e541ac7a2842364b88d47c97d7186f7a9a3d6fd0234c2ea93e71674536870' 
  AND token = 'wYRVZa4AY/lCS7UDMO91uuqO3zNY3hbvSbQFs+OTCYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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