SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e56c34ac525fe2d1d50ab3e50f964ccf2dafc47b3170952e8d146605f8fc17d3' 
  AND token = '6TtJ9/4PEmlxBhY29az82jN0t4XpQhodvVfHIdp/oOk=' 
  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"
    }
  }
}