SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3650e9d3bb61454df650405dd1085e228bea3c98d0dbf1375c6576f1a7b68b82' 
  AND token = 'KHRCT8qh0N8anHyHLN5UwArqkqSbQZ+3jEjr5DROS9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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