SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df7bc7521afeb62fec538602609f67845d91554a0c6ad89ccaa260c7d283b6db' 
  AND token = 'vgb666Q3ctOuovFPeQVCysECJCflNK9ZEXQ1SiVruRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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