SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab8b7835d2180d8e8cb1708aa8f62c4da4baf0828591dc7357467caae80cd51' 
  AND token = 'VpagwDnjdNXpLgwJq5QfRPOxTgv0/6cI8i3Qmqmhscg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}