SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84f6c639f52ddf2d1a42314ab421ae0ae639f83a803b5f01bd1a8c0d2fb15d05' 
  AND token = 'Dvt3L3Ve0ev5lcDdfOrsg0ol0z+5fYNPO2pW5o4djOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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