SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '833b94136d0f623b6af5ed56a892191f250b1a785758b4470cef7503fc4d1407' 
  AND token = 'VSmu1GCeql530qKFLGV34IIw7vuR8FPwceLSX3So2i0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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