SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b520c1a746f415adbcc4bf92ebe46ff8e2e91cf59d04b196d098a5a6e4edc62d' 
  AND token = '1RVwHSxQeRNQpfyPaSfMOHjP2/B3TqHswJCNqEkMngY=' 
  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"
    }
  }
}