SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '777c1bcc4d644f893685aa3785950a445676318afd32028692b069c0ae6b87c2' 
  AND token = 'pf3vKqz8JstLpYxWdvTsK4CzabXIDs7t9GPYFezBmKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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