SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fe1550aeb0116bfd64a352df2007af850b279b842334c3367f12943d3764ccb' 
  AND token = 'eoS+xFrUESuwOg/xMz7jCAgFkoZX4oG5lMVBjZ1/Rf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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