SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d766013d5fb81c0794dc052b459097fa4e5f8fad624ee29cbc825b3da4fb77d' 
  AND token = 'swh/rWWyN+zi6KWaA6xxV+sHtQIaXoQpZzkfBPTFfhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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