SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34f957a5f8af32423f05cb020a6e1351049246bfdc1601fdb2383a06ad3bf857' 
  AND token = 'c+7jlNv2G52QIEkGVnkCNBxA3G5BBMhwyft38weWDpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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