SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '915b4547a0822515dd8daefc46e970c7e0097ade17af254074e67ff536ee9178' 
  AND token = 'C8R2PoRP0GADYq/BO13RLMkozBVERXJd5OdqiDNaOeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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