SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86e998f22b63d17af1d81cf37c7346291a3462f3ead4ea12276ed8e45573410d' 
  AND token = 'ajNkkt3m2uBFf3dwlUEr9TfZg5O4xzktsnd8WGKPtpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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