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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '199a4e8b2da0020feea5ba4804140a03e1c16e808f04e9c691e69e545f4cc14c' 
  AND token = 'VXmSNRaAyGfcqbbJ4NyAwJrtmOxJMT+01Z6Xv3r9q9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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