SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c316743bbc5bf4ffd973c24e3ca01da07818273360daa71c6ba683028e4977c5' 
  AND token = 'iV+JhBihVinzHr2eq7txMEAzXvROyBWgGgSx6d5nt+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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