SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e50358f96c8d59315dda1e61393e64a7f2a59adc8032768c176f451c472b23b' 
  AND token = 'Hso0vFHhk2Z4yUIzgjZDAVZpmhMCTZPZN7nLmrXONrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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