SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99b39ad6f01729aca4314ef1303097b92da34440bb115384a423e870c595bd66' 
  AND token = 'UAFz9/qUW/alNfb8+mN/8YvItMJXqM9hjlOZGGsgJws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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