SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7c4e8895117146144b389085354e0a176552c0bd848e405bba3cf87995c8973' 
  AND token = '/dbLya+5pPRQzQO1HSkLZEBDvzwAYwwPWElQqD9zfK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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