SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '087945853ea24f031899ab735d54727f81af08019725db3e46e3472ba85b0257' 
  AND token = 'e0yaotklexAjU/t2ONavEitAdBp/jk1geAPnJEKrXoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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