SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2534336f0183c296663981d814252cae2ada61c0ff98e99cda3242486bf4745' 
  AND token = 'lDSGZZU6DJIEvduHullZ3ynhCsYNm0RCG7THHmTKaOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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