SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '936fbc2ed959a3bb342472b89306bf102437c40aaf331648354e4c756207ad35' 
  AND token = 'm8RJw+7SBvl6WiInxVhjprecaFA4MwVdH6q9MoQUT1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00079

JSON explain

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