SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39456c5136ea003bf55e05eb349bfcf84ceab0223feea845210847dc0a9748e8' 
  AND token = 'NS8MT0lQq8MJYYV8C5mixcil0XU730ng3RroeVVvhYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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