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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9320b78db7f75bc6933c48e981fcb4342e1aa9ad7255831b909f3335eb74f53c' 
  AND token = 'SjwaI8KPN1sZUuwcUj/SD6B91xrYEInr0cE+g3MQny0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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