SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1acf89938da1386bf2a342a0c22f5f8e2acbffe895b564d396a404653f05f735' 
  AND token = '4zWnmzpuFjUarYXwjVZe851dbRlo+C6rOJbJWXjskaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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