SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12d1870551b2ca0f9b6dd3fd9aeabcd5d6382e5494282f31ce4fcc51a9e2c709' 
  AND token = '/WmIn2JFkDO5ivH3lYTqpmzKMLrohoX3rHJAWaZPLSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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