SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3019ed4a6a4a84aa18be71914518aa65ec871f9315246bea2b36052015ccf3' 
  AND token = 'Rj3o6jhmdJ3b1hwUzDsXQjhWoQSYxDqv1ARUXs0Gw0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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