SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd474816dbf83820bc24dd17738fd52111991c6ac1a4e254047ee89d7e9dae36' 
  AND token = 'R2f2KsTPAEwZNj9d7H2mq7L6lFW/o3AvFbLILujhzHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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