SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a260c08efa29cca9344538b91d508fadfee6a40919833ccf6ed8240ae71a157d' 
  AND token = 'puUG1oH0COWGXei2RrQentdICdAaSV40KiS7k5no/WU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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