SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a511702bf0a416b6f104611a046ca3054711859690e58c2f8323bf9aa1bc4ab1' 
  AND token = 'ob+QNZ8gy2HDbDlIPVkpiAI6e+2FWkDiNSEKKGH2qBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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