SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '249619e2d6763083532742604c1e7244136300fb006fed3cc68b71add0a8273c' 
  AND token = 'fVAt4VwDaLCcQaTP/+4gCTFZU3lanHlSa+pCEBozKZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}