SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5afcfa98915d0337610d6314cce803375864f590b9174dbd06d44be56897a7e8' 
  AND token = 'LXBo8mC47jhGOfDayBPhokpKqkmdoY5E7eylmrW6lDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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