SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '268814253868b4bce6abc3295365cbd50425a7fd98337c319909950703fdd042' 
  AND token = 'urwYAN0Dtp/w0z0c13V0RaFpKLOOHr+fOeqRsBwshdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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