SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de3e6b1d11636763d7a7b49d4ed6758e1225b5271ee2d5d0356855277b8540fa' 
  AND token = 'Vms4Bc4pztoTgjuZIhjCYa4vgH+gG7QcJSVmj+tmq5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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