SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39865f427458b5c7ec73cbd28d74a3308781a7b8a8528e59456046eb7facbcc8' 
  AND token = 'l7rA6IZU2kkcPBzuv3vGoz5YxGcSGeQmPVSTv8GyBZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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