SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd028ebaf41ef120f1017da5db463462ff640acab2b709d125ce367c688f5ccdd' 
  AND token = '8NmryBy3avNT9wPQfYXnNrG/z7u4hie6CjT8SGJq4UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}