SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd83a22d43e21a34a5553946cdedbe948e2c46b587b551c182417544929f07915' 
  AND token = 'wHNWBviTShnlRZCRkY/gaIMIvu4j7uIPlkOm/xf+wZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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