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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '874f7e9dc3ff6c6afe9383ebf84c639328f746341691c49a9b6d9cf241c1da40' 
  AND token = '+8OKy19X/9AZt9mLP44ZfOF3kf4wKmDynHqY7gY1JLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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