SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3979820a43b6f8945bfa56887527a8aaa8ebebcffeaf194e16759200876e5f1f' 
  AND token = 'dTJXWaT3aveyOLhXJj1O+DYr1lVjSRYd8feEchjarKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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