SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29bc37ce4ea3770bc49304921aa37600908ffd728a368186ef2e04d63aee401b' 
  AND token = '45ytoFqeruLZrf5QKwYNsUXV1PKhJRIzkTZEjXJcvYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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