SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c29d3500252cd04abf0820c7dd11c41bd823219c4fe365039330b25c343e3c50' 
  AND token = 'h0xFVjMxVU5Vl1h6cx0AY/CXs5XppHYRoNgCc9RXKgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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