SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '654ade72394720ce8e191f24da5634525d0268ee3425019599987835061ce86b' 
  AND token = 'VlGSAMBUg/kU4TjON5oWe0UwZ7zKuyEmM+WrFhyv6z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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