SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14fcdcb211cff71d4e08f59b19566584bb5d5b8f8785920c6647a4ac02635263' 
  AND token = '9h9zLWAPQicg2t+ZwcO68xUjGgwMzHSV7w5nSprcgu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}