SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f208d84333078717bf379669b0b21819745a073da819b38ff7b0a612d817858d' 
  AND token = 'd9mpAwMnbSApDrXyhNJ/hN7geEn7HydsTwCz+YjYcPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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