SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6a4b7e814a028d816bd635e320fa9c73a848047bbd9559d408f65c2d77a0bca' 
  AND token = '1hLGz4O7WjvsJOgSKe7Y+2LAQoDslXwexxmEepPTRtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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