SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21091fd90412a8c429a08e2825c578577324da7f24f268de4ece74aaf6fd5eed' 
  AND token = '0jKLJY0G8w+XtHHfkfQGmB3ze7E677T8KNxXbQTWXKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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