SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4cb2ebba327e6c738d4d89284f2d14f13a81b42b390ae769de33222f798350' 
  AND token = 'OqXRRGizLZpTxVKSNoZ//8TSm8SopvMPqZaV6EqzNzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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