SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49b4dcb04add7ad475e118386714b76c891f7fca5cdb85597deb1252c1a32228' 
  AND token = 'WptnCtClIoN7yB1uJYitEGDFU7F6ak2YPe0CbBccR0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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