SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be7a45e8484dbffb1eeb5098b435037dcb91fbb0d60a7b13f7c1badf1c66a8b3' 
  AND token = 'YhuKV7nQk9pvBQdbsoWOH0GuLcd/b8rPZxbSuAkGZCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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