SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85a7eadd942a147312f13546868e4bee1b45ecbd879d0c7d2d83be241394abef' 
  AND token = 'RiXtWuyGfnHSY9A7IhKkVE/CaLo6F5jxe6EHsshrs2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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