SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29f7678bcc20e45f14ead668d04348303441faf12a972c32025672d8e8be6fd6' 
  AND token = 'bcxyMugBq9tHQF5fVOrbyIFtW4rFwTuLs2FRDKZvY/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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