SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fa7a0cb6e3cab98b8a35379f92a5b276a587b4eb27d974d12b500b8b6744544' 
  AND token = 'MKYwkGSlEYhHDn9p5zW9TOwUPPd1qFbN6BKy//+9Aak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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