SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6bfdf251d77830672fbcd4de0cde757f9b6a7b8086d23168c29fed9587fa326' 
  AND token = 'bzhSv/lpVYPTRPLfWb387RVBYNIiMtrzPB99SpwD28o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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