SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67b020a9e917697de550a5cd6fca44e571eafd3fcd02c41296f329287240aae6' 
  AND token = 'aE5A8EJuN183bXZ/KjV1wRdCWDzvs+FWuyY4z3gvYtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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