SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c0e89e1d395bcce7837eff45bc58fe181f42be03706f7595dc518789cbd8751' 
  AND token = '1uIhNRKTsMyenXfLI29Jq7HB/fI5Bt+T9nkW9Dum3tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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