SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '438227a72d1583662586969951c93ccaf4df60788321e52104acce1ba64ed024' 
  AND token = 'qYjfQ5fI7BCMfSPLjsVdAwsrInbL/neBxeLTG88yxKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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