SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0c6876f39e63d07f151a5a7ce4840aaf98f3abcf393a14340dd67df65d3823c' 
  AND token = 'TPSgElr7/meRKRWOWN8fbSx7AC6zz3LVF1aYckhFTHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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