SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70fc874cf1493f89390262275fe95bac730b8026bab48d7d56b4a3ea26697add' 
  AND token = 'VlqwHy4msTBwrpHEAvYYJzR51GwMi359/gyJCnPo88M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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