SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fa9cbf406a48bc123216aeff5e9864616251b23d7781b726f014846cfad5c4c' 
  AND token = 'nzXqfsuNeS5ogig6Fu9hRxz7ZrfQ9x+XkLFx9Lfzk1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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