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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d069e5f52b79c6f1bd3d8c2130f26195947be7cdc5b751b890ed9754ab3e73' 
  AND token = 'mreqUPKZZpdWBhhN18kK/VdTDM4n5hQyrdhM/IrtRkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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