SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55e8ef1464078935c8ea26ec5d9684d4a8bddec356a06cc74fb1d9e0487681b6' 
  AND token = 'VYpKUcGjW1qC201kKaKWiH1WXMt7MeK5y1szjVaulgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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