SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67d6259906c3463ecf82aa37a299977e2eaabc079b69ff256024924f3e294da9' 
  AND token = 'kSoNsJSxqiuE908HzsYlfCW7NjHc5Xzjk7CbLFxbLaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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