SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '640655a740b86ed56ca99b3fcc2580fe29d1844b4792eb3f7676ba0a71f7f262' 
  AND token = 'hmlsCdGWPAwRIXd+bZK4jDHLKW3YSjwoPTAz+Xbe5uA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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