SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd99528d18c3002fa532e752a3849a186de0dbcfb01e10b41b3b78ad959775a97' 
  AND token = 'RPvTFW9PxGZCK3SHZF8BzS6wJD2wzWMlpVnIq0M1mbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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