SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b9f21cca12048f72e76cb0b211b6957b19d02f843ed5f8c81fbb108c50a5092' 
  AND token = 'TF8uBRoAxeWZT8PTsryaAOJtfXOIe0TLMkQwFKDt8BU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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