SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2930836b490a40fea0e97bfa6948c3ecf5a6dfc97cfbe23c64c36212e18ca15c' 
  AND token = 'YT8yoynNrbtZUUVkCjZhz8jj0NTqG43ftFkF9xIY64o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}