SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '765957cb359961043eaef5c17d2afd60999bbd73da8fc981df950e652241426a' 
  AND token = 'EBo6AzP5wIl1Wep+cEQDjO8YEEo/elOR+Aqa0A6ZZP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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