SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2d0387b0475e2a58df3d5b520fc3f876fd0a6497ee49683beaae2d0b52f1340' 
  AND token = 'DbJb5oxZP5/xzy7NZu9snC4XXC0IXgGUZfq0sgsGIFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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