SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a5692b40f15cf138d349a28ba242f2f3968451e001b1e30c314b36b49ca7149' 
  AND token = 'Fo0692Kjf1M9RNC04LcAraxgVFNigfmlTU2d+MUJOVg=' 
  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"
    }
  }
}