SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6f5fb59ae167cc0c613bd513269ce1b202335b3d9b7424d1ad5329fd014c3df' 
  AND token = 'VyN0/HyzFFXqLwrmltgrFr6OuEoSyhEGujdtf2wZnzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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