SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78b62ea658f83d7a7afcded6784b277301b18c14b7457265b9faa7f65499c16' 
  AND token = 'DPgn9QiihPKvscafCbEByccWIt7RTeO/XTNk3Cq0nXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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