SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2609fb4f2c011c6fe76052ec44e3357fd3785d476789686066d33830bf32082' 
  AND token = 'HAzcEWbAcubDgEmEVpXu+sg4pcXKwKPYCRh5ERddshA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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