SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a73b8bef4d3bfddc6f733aa2ae894be1f5179632306c239fa8d5ff473646045f' 
  AND token = 'WbmlsJQX6eioH8vi5M52HwKa+vq3+XPS/it7rQZGJpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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