SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8a09aee867315c7043f0516d78e0dbe48d9d44e3bb311421928fedb4545fe28' 
  AND token = 'DQdznSCgH33vYIKqxjG5HNimYI8IHw2dnhQybfUQZvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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