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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e66ed23f62928e0a63ba09df7710562775aa4d7c5816d7e5c50c4eaf40a70756' 
  AND token = 'hv8V+9cU9ZpnCoZpHTdaTzXmTSvNVh8sDqUaF/FEtDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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