SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de29600e963c469c2724187201f3fccdafd0d722ab5271d1fab05ee766de2186' 
  AND token = 'LxT/ZKi7aCPv7CAsZPOBj52JZw2yhhg7bEpR4FyXhWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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