SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de6f4953a13ae70ac3ce71fd435613cd6f23fb420ccda0053474ae84276ba79e' 
  AND token = 'NxnUrt0TuDRRiTzJ1KmSf6EeTYczDDElsjaj2V+oGEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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