SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '501648135d61558000c12a3241af9d67516ccb7fcd5576e6d0f32bcbfa366eff' 
  AND token = 'PZzVhoPTPjfLuNqLo2Q70bsSgGECt9GBDWihm/b7rE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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