SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c2bcf5261abf4b865732ef967f1fb24eaf15487b6c5dd98ec767d8653a3881' 
  AND token = 'qcHmfsa+g5FoEJa6BZ6x4rhY/PqjxLuVukhQh7aKiDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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