SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23afe7157f640daa69ba94aac61ae105a90e092f92e8d1910a78be5768525c28' 
  AND token = '5iBFjNVf/pGY0/kGMNJPipXRMAikPKjth8DgBRUOhYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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