SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '399abbb57eeeebaab0abbdf985af7679f561a381cc2714ecb71e73ab6daf4c39' 
  AND token = '2RSvLyquSujKkh6YIaQIsAHNupds5ppdmdqfRg4r/zw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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