SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a91b3fab3ae3cdce7a8b20df7f1101912cb34d7c436b586d239172a6a373c47' 
  AND token = 'uhPXd+53E/7UVEXk8BqnRO6UEBEy42zRlA1/Wy/8zMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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