SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5957273ffc11abe06861afce3d1b980954289b2ad81e5d7b85689cb64253def8' 
  AND token = 'TmPKWIjb7ZeVKJsOm1FsunUD1qpZMJML37w9iBrO83s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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