SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f512552f26790a9e665d4bc8b533a763fec68e523893240fbda6ec9a2c6ca8fc' 
  AND token = 'aJ8MSuMh4HF5Z02ngqAIQrEaGi5dC5ryjly/gcnrMuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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