SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6df72a733052caae0a7ec1f2c2444a7429e98458afb7f68146dc6ed54d1f527' 
  AND token = '3XXxZrHxHDKb+hzzx3TvlzXeqW7miqy5BQA4JMfdqcI=' 
  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"
    }
  }
}