SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56abc797ae50667ffed9284c219776cc84cf38ac78da594e4317404c77502c9f' 
  AND token = 'z5pqYLavH9qId/2h6YYHRVbJsN7tN1xB/JsbxG0/WlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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