SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '877f39926dfa2eda34326d609fee9b3f4aa2a7fe4255b7cc3963be023671c7a8' 
  AND token = 'eG8W5r9bbq/WAsS6SfA2KZoXaVGDzdvSXtRxTK7SQ8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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