SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8768d23cb1a32d331106f49a15066efee3be691629f597d5afe8e44718fb3be3' 
  AND token = 'nOni+jWwRQ5tt5m7gr5RwdmeqXWyLYkkSs+boHWFe0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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