SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d5cddce8e2a6b82056ed57020d93397f42702f5a90d56cb7aee8657099b9521' 
  AND token = 'MvCeTmuHQxUGe0FxzJHCCDcE2fI5tZYbd9VkHtUYGDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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