SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27e60f43b958182026e8ec295458db097a9d83336f49a1860f309aa426ace5eb' 
  AND token = '8mo+WoeL0nzorMcLuRE3QFgkKbrt9jHNajo+nRS0GWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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