SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cb1cb3b49db38df7e2b7f94483abb663761d21c6b8b3acf654056c4f780939a' 
  AND token = '4oZuH6yjzNktE/mjI/Jw8bfryWHvRZSJpTKgw8/2ShU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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