SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fff68dbcc92847f7104eb638e3c725d2bcd260cbad8b6d7e633a4d856a3106b8' 
  AND token = '+Wn/s/0G0BfakVghqrzxPKFyW9sP3pdvMq1jyIxVyd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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