SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ffb289c30ec5664a3eec62ce19f0b69d50850921a067e0828ade5c9fab813db' 
  AND token = 'd57CM9i8FNSJfyXrBuzGTY6OxoOchss3PA2eONwUEmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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