SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759a7a78218ac727aabd6f566102d2e5640bc01708048dd41c9da2bc34533274' 
  AND token = 'Xrc5uIakOxEzw12Zm7q/oyj+T7GkDUzoum6tNOKEt0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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