SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '012b821ac5f851aca19e7746a5859380a8cd34f399e00282a015aaa76b10c5ed' 
  AND token = 'VEbt59ipGa0RCf5Nlr+1RKHTQk3HU262cVH5mlhBE5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}