SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2689a74dd24d543db36d57041a37c1a2e9b5398a30c7261aedd38aa81ba87c71' 
  AND token = 'RRr89r11o1vOLuBkFPxnRw7xpP8/JcEU1HkWPyRcQOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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