SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad20bb847674af7a7623137c796960f6f24a5a7f7228a517df6f93d0f48a3e55' 
  AND token = '0GlAgPnE+hy1BTZ6Bzt/cRzuUrx6FZuosZm/1NllXPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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