SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '903e13ec6528e3bb97ea29656f4efcbf19ab26ff34e6f2f7bc8b2d90fc796417' 
  AND token = 'rVtKz85Y/6qI42WMLcHZkzA5m+juDCoDPveBpiyzv4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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