SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12c8b9286bd253828260d5524cd3d733641a19a339790c524cb7c772acadf197' 
  AND token = 'HtxLxmCj5CMUhQRBzer7dYtgmXa9PD/sgLDjzxIsOYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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