SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f12f1a823ba246572e9e607740b832e4c5432d39146912a05fa161f618388d0' 
  AND token = 'YWgx3PdbJ8xWP4FFXC7egYOnky98zSZgBYgfRIYDY7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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