SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fb8272b780a41eb28b5584b8149112a68a12576533b9433b226969df0647bbb' 
  AND token = '43fRP4tK+2TJktC8LerD0jWUxhCVzYPM18pPiqwVCFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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