SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b4ab1cc21a443ebd9c553d689feb81ac1da75068a0be93af551ba77b481ef47' 
  AND token = 'z/hOb5+8nqURWDaBZBj4dSqRPo4LVxEN0MB6fiX7JJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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