SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3299e949466cf3bf710cd2f6cb76835c93ddb23d241a222f10705478eccb783a' 
  AND token = 't2KgWjNagk3lvv3vEsuXHKrVyliOF+FIo7nzGddkrn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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