SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6a6ea3992005eb61ebcc72305b8b69d85382e358e906ae76b3272e7e91fddc4' 
  AND token = 'V3DItH6LkrK//Yvlm/uIrbfzK4qUJC/9wWZDs0GVBfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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