SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b047bb2a78449c83a1c7b58906e35a50737cef566bb96a33b6777d9ad9ed988' 
  AND token = 'qbg9vUj1nzu764DiQRL/+nFYOrqKrJGqxtc3lZ7z2Bo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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