SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d4f434f7b992306a9e511c2bd41b0eb2a72c5f785a4091d4f0c2150dde61d22' 
  AND token = 'wWwa0KSrj7Y9GiXNH3FrpLPZ+hi/i0fhyPFRIjmJ8eA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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