SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '177346825c562377196fbf2382ac948e6015aa1d9021deb038caf2f4b430230d' 
  AND token = '+TvUc+2TWsU/ZWPpwgN0wc21dIZrHSebtffHqxtEAZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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