SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fef5211775cd6d39b344b4f2d77a51525b3a12fb66b72fdf53d969a68e973080' 
  AND token = '9qKVvpaqNwH1fZZQRJbhWtSDBz4nhMw1JrX7dE139n8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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