SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd0540f778019b5cb89e4622af82afad73bfe3281d1d75bd021a113d4bda16f5' 
  AND token = 'XsSFckXN+5gJOhYHgAGuoRKh7Suex8IF+C59UrGZzZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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