SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b91d3d7787814b9798f82267a6eb0dca834260095083659a753c44b537002663' 
  AND token = 'Sd+Dbljl9Fq4Jhuw9lTmGJj7gNQYDjdRKAb7WH+AX5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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