SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e4b13b13f0e2e34f8d36012b5c7b0e472bc1aa2425e8aee05409417fc157d39' 
  AND token = 'pPVyh/0EecFwVYSjwNhsRygZ+BTAulszsawhRyIpg9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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