SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8b206b8770a7c885b687a2751f3c73e8a8b82b7b29d7494f59177a107c34e5' 
  AND token = 'Rlw2L5XwNLWfWljvk4ZPrVS/h//dCWCqPvDQBe5N0wY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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