SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '500b25a16978a06011e100d0e7c58b67cb30940e046d643948e143381e9c56ad' 
  AND token = 'O+tc0/w9+gxYn9Hp0vD6VXNNvQzCnXHIllZxMkIMnko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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