SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48491475d1a68e837c96aee00b16b18fd950bf5586c12ec2ac4845f63e6e8f37' 
  AND token = 'Iyq3bPqpIjVMDwbG4ZLzAvoaRABf3nmJ9AWoyLXTpFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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