SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c25120e67676bcdc701cbc7d8fca28d47be8052cde1294ab5758d714c93b89cc' 
  AND token = 'KKXsBQUolGH1JOKAd/gegrXlgEHdWKtxxC3xayc7zHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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