SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '798cf3b93b4860586aada1fe556c98d5cb7857f3f3580722acae33a14fabfb8c' 
  AND token = 'Fg011SXKNVh7OlGY0KRyD/7uyvg+PtgqHnKZhLtBqP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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