SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b91bdb424d328b3ff048a38d872843995bd0ebfd2e784209159aadcbd38c6ee' 
  AND token = 'gTlkh9WuDsKCltmxuLuRNYc1/3Kq1oZcyRcrWVE2V7s=' 
  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"
    }
  }
}