SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a69bbe6121765ac8ef389e59c1209cb51c0ffaa350ff7882f1a8d13ef48c1eb8' 
  AND token = 'jDXuG64la+zvJZjdXJTlT+5lEdXgx1QNALqxg990BwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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