SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '767940058e4f598170036a4e0cbef0276e2020c5c457d839ee3354cbfff357f5' 
  AND token = 'NnEPsj0REA1WfkqWIwv/3nn4qTWhLO9gTxivGykjYxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}