SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82d81c7525433d589650114089d760e8a28fdb4816cd0e0e8e330ad6305471c8' 
  AND token = 'B0Ps40cOYsF4nybXlZzicxXLtIsg++RWGrH1KXnVsvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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