SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e4f2efa6052823c1e1947959dd6a8a44785d24ce9ef2e53d6af0fdaa48b139b' 
  AND token = 'BMhN+F6Q3Au/CpAt1da6dBLvJY0ZOlBsDOoIKVCxdqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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