SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19700782810afdd6ed433aaa4b1d2301e85cf5404edbd1f5e7daef13f99f5eb8' 
  AND token = '5MwZV5dLNXJ1HQ3KDNfceSJjJRLCd3whk/XpFDS9kz4=' 
  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"
    }
  }
}