SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42203c845ae73ee748e6afdec009c7f5065dbca3bf11af4a015fe16fd3aa218' 
  AND token = 'WvBqATAbJ8fxXZx05vEAECsEDRmnl77xAnHc1UDZwdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}