SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f82bcf9283aa0b5ad9a30a96ba155fe192e96b42ecf3316873bd38e7de665f' 
  AND token = 'LubMqqhvGGWJPC7FeGx1XzB52rz1oQXDJGSNsp6hfwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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