SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '999cb959cdb87166dc8b77d2f28a41e50f7e95910ddaaa122291209cc1d68c0f' 
  AND token = 'AqkxdnHkV+M358dKyNk/RLQV71PVVhNxYlypYP8lqA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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