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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17ec84e7a6e2a17d313922dc5a43de46a81dc8da7435b576989faa8e42aeb1d7' 
  AND token = '18RHZlI/sInWGRGwDQXWurDLh/6U/Anj0s9qHVSBSBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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