SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3af6055887d03f11c237131ee1fe3161eddd892079a10b93485fcaac8fa018d6' 
  AND token = 'hj4xGN+wxes7dKc1HWj6FnKWAzZzXudq+gpycEqBGMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}