SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5918c7a4874bac4f9153874adffe4f7b74be49a6aa9666d5813e1be5105ef893' 
  AND token = 'DaerIH2oT231z6KX9gpxkGKRli7GXYSLMt/cfDACci4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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