SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '878faeb4cd878a641cf5578a435fc1a4b155b64a533084ecbfa221a723370d1a' 
  AND token = '1YyDx6qLzWFZ1SMgwFlXGQgcY6KFJAtT5y5kfrfnLn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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