SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55cd14a4142828962f9ef1fee7012c814cf40883ce9877893964a401611d35cd' 
  AND token = 'OutCRn3PnGYOyNYPGR4kBv9kC+rxPDjf8qAUd22T4o8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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