SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '500eeb0e114171b6990d7da3ba9802bddf5a78433f5e689aae639b70bdb555c2' 
  AND token = 'epWjU3FuXtYIyAtoMXDXzjAWIGznet6PgX1jDGeWWCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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