SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1821e61a9e814a571284e78064d52e99685f50d6251836f186f56df4b1fd6dd9' 
  AND token = '45VjHrwG9eXK38zpKfspbhCv8amEV+c7ySUMZxIgzOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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