SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c340a32c270efc7965302d9bd48ed3264927806f9ed3a882bf36b9770ae27c0' 
  AND token = '+TxcrBpLUoSjybCTgYEV4mf5lLWEh4SJBu3DnX5DAfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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