SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6edc218582b675df78cf4b3f7c58882e39372bf3357e716584d9183a6aeef8f2' 
  AND token = 'ZB+kOeEIUZVzXkGmU375mtzseovZz5mG9DcfKykU8cM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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