SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '734829814737e48e565f02753b4295a962f48baa8ba2facee668ceadb3a3d88b' 
  AND token = 'xZghQi5u2pkvIUGAd9iUvQP9d9NpNuHIUQtKv5harxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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