SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de7ef2e858478a9367f102e1a6547f557b82e0dd94018ba5fa429a9621fba022' 
  AND token = 'PgkFKE8e9s7l8HV2Aa5l7BM+7rNAMvNfOmCZB89tx80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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