SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8df885aaef124bee4d251702db7cbb6cb9c04b5c8e6de7badbc7de0ffc76a7db' 
  AND token = 'l8gmXOiUnRZd4D0RKBGdC7fUAWEMgBKcQ1BKEMky+rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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