SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbc0949e7df2a7c642c6bd0a30b319ee426932498adcaa9f601c6748ad1df47d' 
  AND token = '8r3Lf8W1WoKW39lvgQZXWAkDy4hfwK2Eet+duDIBA4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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