SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c53d4b31a5622e0f41a806397bf12fe6cc160ecf9cdd09204a5f29deba321a7' 
  AND token = 'Nidb82npA5ZqQs4tx8Nbzktoa/hrY+uBhQ1kbIZ3bmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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