SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96fbbf6a87cd4b5442fbb095ebd3a537f1c7abfb137962423c1d686fd9a59543' 
  AND token = 'x+YlIofQjcCcbIHvgDo9NM4wJTKKDncKpT9DMd6+LdM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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