SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bd33545a1f440bf99cd2f836338aa1b869c37cd909d30f1a81648e1c2b4c362' 
  AND token = 'uUr7yLcTsMC9QfmBlLo5Hz9Kj0EJSmZgDUJ/vj5plxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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