SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbd5ffb74c4534666786710c78c2e7915ea69e11c5629fc15a8753f59084b499' 
  AND token = 'Hd6v6JhJ0+/sg9UaAFlHlkH7yXEoRqXXiAhrmrwIbu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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