SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68be107dffe13593acb8993a68f9e325d5ad7469a35ce766454c2f3af9972a8e' 
  AND token = 'bE5Q0DJjEhAzlITcthrdV7aoKNfmmyIzSJft/zCYSr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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