SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16fc1531e3b13b0f606e31e61de8ffa1a79e0302ae8b60313420426dd7e05aff' 
  AND token = 'sRprUMM84Wt6Ovl5gsZuoBVjRwBsXb4bUtEU2ghAZzk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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