SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cba6b64aee9c7ef34b67b60f2360e4af04a1b1c8ca1c8222362d0e3a3d7c29b' 
  AND token = 'VeAkPlBiDrc+cKtYN71Tvi/DyXktkewEpnnB8f64t4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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