SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2eb1a3661e0fd6b37259692280de66211c887520045d7235f60e5b22223a4db2' 
  AND token = 'nx5ueTdue8jvksgd9TOuEHygyQivBUOixZ/6rHLNYRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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