SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '724ba4fb109fa3710f9c30a46aab2bb3f870547d0550257c51cbfdc31f8fcc4a' 
  AND token = 'AY+uMDWUhcFyBvT64tUGRLZ8rVZR/ykWxcpPaBdWGCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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