SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391512aa61bf638a2b435d4eddde6f67cb5d0a28cf3cf5526b532d66f833d158' 
  AND token = 'Nh/Y8/NvrE0Dm5PTYDEq6wrIjhWwUDsMKllFfNYpmqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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