SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f074b7c7085e5326665fdb3c70d2aed9cb6abb74d39b2a8d195cf6f04b0363d' 
  AND token = '3DSTiMGs+mt8JxT09nvQAQIJlnuDJ6uEHG58ssYeweo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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