SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76fcbac44ecb792c40d9c6fd393c02f8bdedb197af2b93257d2700117e096b28' 
  AND token = '0dgRWUdzEBkZh68t9oMhzMgkVkmoqI5sLPVVJAMJKBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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