SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f69a6842a40d1bda9fb3f5a212dae528340907b6ee295b1623e9dab3a826b23' 
  AND token = 'cTwZVTqWNXJ6bN2i283ZCKVVhqL7FeTCalNhnwqeYUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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