SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5c940bc83bef9962224f94bde47a43bde21fd00ea909378a9c238eb06bffa71' 
  AND token = 'M9WxMjlvOuO7zREErg2zUCeyPmecMd1aGhftk3Jvtcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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