SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd685e4d7cdb27ff1020c7f6b4e5d1f13a9db0adce9d80337a2621c80742a577' 
  AND token = 'AkKxuDVZ4uIWwJeqZgIE87712LJy7dsfCwUaEyCElKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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