SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f79c34d9637fce21d30a5f1820738fc27da5719b0d4f465b0c00342a486b7f15' 
  AND token = 'Zq8agYP/o0hz66wlnNnWkDmNVBPa3OAzntJkgpCXe58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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