SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2968c03e0123351c53c52d4f9e438764bcf365b01ed4dd6e8cecff2928eff5c' 
  AND token = 't95+UPi7OMeUaP/scuWHs6jXsnGSsSEloWj8DlI0pZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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