SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8b8827ca20e8f27eb521adb792c949bf2b1f137f043289c5358160ef4d80635' 
  AND token = '1ddM1krGTb0whT6xQnm9OD5Pfw8U2nhTsoKFY+f8n/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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