SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '876b3491b9971ed489f49405a5edb769911ece3e9f64665f057133328cf7f238' 
  AND token = 'xF0zPbqZ/eCb2wImZywO6V8YdNZdzjKw+FatqkK1RCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}