SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35d1ec9e5ea2fd9eb43505228683108f0cddc1bc889f56a935647ddf15dd0bc7' 
  AND token = 'rBVtv8tC9kg7sAlGvswYRnn7VvKYrHfoPWTnEkJmOdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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