SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21c1f38a388575a6165fb7af967caa7dc91fd95f933dce98bed14cf8b55452ac' 
  AND token = 'Z5lFJdQbgYmhkVM4btEOYPlVJYDBjUkBqLlqKhxg7kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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