SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fa0121b4235bad12ab993591d5a25971bf197d1ea2090c23943241706880e70' 
  AND token = 'fSaozXmIoMIeFtEVuptCJZtFkFDs2pgfbfn/omM2ESo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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