SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a103fcca6573e03faf6755f042750c35f863f23bac7ec02ab9b57e32f641658' 
  AND token = 'j0oqfvAYM/x3eWsPDLG4EqwyOYzGg7rUDZE47i77WbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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