SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77dcc271793219d220a0b301a58367e31cb0cc5eca86430f72b353c98ec84e50' 
  AND token = 'pwEthMiiV76zPIlt3FRtmqOcxjWkNXczBBvYnLzNx+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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