SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e9916056b648733131ee2150e02df1cbc9f624d5fd11dd535a5124aaaca5966' 
  AND token = 'bMgOnernMxHSJPTDvp05+c9GFc2tapjVpACvHGM97vI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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