SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9394d547dab172ca4756289f38c1fd283dcfac6cbe39018986c06313d75946d' 
  AND token = 'nje/I+qBGEzUlxEQGerGWOhv6DJiPaWwIG6i6r0KfZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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