SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15fe73f5debfeff7be0743c66311bcddeaf41e6a4b3e8664592f414c796a9908' 
  AND token = 'qIMVpduVpuArW8e6tRtGblQ+a26kKbg/lpp+DiHbuoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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